When moving materials with a front-mounted materials moving blade such as a snowplow, a not infrequent occurrence is striking an object, which is concealed beneath the snow. Modern snow removal devices, such as vehicle-mounted, snow throwers and snow plows are generally mounted to the front ends of light, medium and heavy duty trucks, front loaders, backhoes, tractors, graters and similar vehicles. Snowplow blades typically include a curved mold board, which is mounted on a frame. Snow throwers and plows alike have a wear strip, often made of steel, which may be mounted to the bottom of the frame to act as a scraping blade to remove snow from the ground and to direct snow onto the mold board.
Roads and other plowing surfaces may include a variety of irregularities and obstructions, such as manhole covers, rocks, raised or cracked road situations and debris to become frozen into the ground. Such obstacles may lie partially or completely beneath the surface of the snow and are, therefore, hidden from the operator's view. There is always a risk that the plow blade edge or other portion of the plow will strike such an obstruction while plowing. In addition to such unforseen obstructions, known road features, such as curbs and berms, may be hidden from the plow operator by the snow. There is always a risk, therefore, that the plow operator will miscalculate the distance to such a known road feature and fail to stop the plow before it impacts the hidden road feature.
The plow blade may strike the obstruction with significant force, which is then transferred rearward from the plow blade to the plow assembly, the attached vehicle and the vehicle operator. Such impacts may be significant not only at faster plowing speeds of 25-30 m.p.h., but even at slower speeds of 10-15 m.p.h. The force of such an impact may not only cause a sudden deceleration of the plow and attached vehicle, but may also cause the plow to violently and completely stop the vehicle. In some cases, the plow may deflect off the obstruction and jump into the air. In some other cases, the bolts holding the cutting edge have been known to shear, causing the cutting edge to flip through the air, thereby becoming a dangerous projectile and road hazard. This response to hitting an obstruction may not only cause significant damage to the plow and truck, but also cause personal injury to the plow operator and other nearby vehicles. Although driving at slower speeds may decrease the damage caused by such impact, slower speeds decrease plowing efficiency. Furthermore, driving at slower speeds still does not completely eliminate impacts because, as described above, obstruction may be completely hidden from view and, therefore, be unavoidable even to the most careful operators.
As a result of these problems, various efforts have been made to design plows to minimize the undesirable consequences just described. This is accomplished in one of two different types of blades. In a first known device, a snowplow blade is mounted at a pivot point on a support structure using a pivoting mechanism where the entire snowplow blade pivots when the bottom of the plow blade encounters an obstacle. Upon impact, the bottom of the blade pivots backwards to absorb the impact and the top of the blade correspondingly pivoting forward about the pivot point of the blade. In a second device, a trip blade is hingedly mounted at the bottom of an upper blade and pivots about the hinge when it encounters an obstacle.
Such materials moving blades and snowplow blades having a scraper blade system for scraping snow and ice off a roadway are generally known in the art, for example, from U.S. Pat. No. 7,107,709 to Hamel, which discloses an articulated scraper blade system mounted to a snowplow blade length and installed in front of a vehicle for snow scraping. The blade includes a multitude of carbide sections moving independently when they strike an obstacle in a road surface. By way of another example, many existing snowplow blades are equipped with a blade trip mechanism, also referred to as a “trip edge” or “trip assembly”, which allows the bottom of the plow blade to yield (“trip”) upon substantial impact.
Conventional trip edges are described, for example, in U.S. Pat. No. 6,618,965, entitled “Method for Absorbing Bi-Directional Impact of Snow Plow Blade Tripping”. In general, the plow blade is enabled to trip upon impact by mounting the snowplow blade on its support structure using a pivoting mechanism. The plow blade may, for example, be mounted on the support structure at a height of 8 to 16 inches above the ground. The pivoting mechanism enables the bottom of the snowplow blade to pivot in a rearward direction when the blade impacts an obstruction. The top of the snowplow blade pivots forward as the bottom of the snowplow blade pivots rearward in response to the force imposed by the obstruction. This rearward pivoting of the bottom of the snowplow blade in response to impacting an obstruction is referred to as “tripping”.
Typically, one or more strong springs (referred to as “trip springs”) are mounted behind the snowplow blade to resist tripping the blade edge except in response to a sufficiently strong rearward force. When the snowplow blade is in its normal (untripped) position, the trip springs are under tension, holding the blade edge in place. When the bottom of the snowplow blade is forced backward by an obstruction, the trip springs provide a resistive force, which tends to absorb at least some of the force of impact with the obstruction. The force of such an impact may be reduced by this energy absorption, but still will impose some deceleration of the plow and attached vehicle. It may also cause the plow to violently lift into the air, sometimes by two feet or more and then rapidly fall, impacting the ground. Then the ripping force imposed by the obstruction is removed, the trip springs provide a restorative force which return the snowplow blade to its normal (untripped) plowing position.
Another issue which arises with such materials moving blades is the tremendous variety of vehicles which are used to support, carry and operate the material moving blades. For example, a particular manufacturer's farm tractor has an entirely different mounting geometry and support structures for a blade than a truck used by a municipal entity for clearing snow on public roads. Both the farm tractor and the truck may use the same blade, but because the geometry and support structure on each of the vehicles is entirely different, the blade for each vehicle must be specifically designed and fabricated.
Therefore, a materials moving blade manufacture expends significant time and expense in modifying the mounting fit-ups and welding on the blades for different vehicles. A manufacturer may also have to produce and stock a significant number of blades with different fit-ups which requires an estimation of demand for a particular vehicle which is difficult and inefficient to foresee. If a customer desires a blade for the farm tractor, and the manufacture has in stock only blades for trucks, the manufacture cannot simply supply one of the in-stock blades. In this case either a new blade must be produced, or an existing in-stock blade must be modified, and either option is inefficient for manufacturing as well as inconvenient for the customer.
Furthermore, a manufacturer generally stocks complete ready to ship blades. In the case of materials moving blades with wings, the wings are attached during the fabrication and production process with the result being a fixed width blade. The manufacturer stores a certain number of these complete blades as inventory. Again, an accurate inventory is difficult to ascertain because of the tremendous variety of vehicles to which such blades must be attached, as well as the desire of a customer for a specific width blade for their materials moving requirements.